DVC 2000 problem to fully open

We are usign control valve with DVC 2000 series for simence PLC we have problem when we tray to fully open this valve ( air to open type) by 20ma output it's getting bad pv because in simence plc electronic card getting more resistance by rising output 20 mA so it's rising bad pv,

so problem is we can't fully open 100% this valve by 20ma always have to open by giving 16ma~ 75% open or 18-19ma~ 85%-95% ,

Quastion Is can we configure valve instead 4-20ma to 0-16ma for 100% span or can we set 2-18ma for 100% span so our problem can solve, resistance will not rise.

Anyhow to open valve 100% we don't wanna use 20ma so can we configure 0-16ma or 2-18ma output for valve at DVC 2000 side ? cause, I think it's possible from plc to set this kind output at plc side but from valve at dvc 2000 I don't know….cause i know we are gonna going to change 4-20 ma philosophy by this. May be it will never allowed.

Any suggestion / expirieice most welcome to share it..